Treatment of hydrocarbon oils



Patented Feb. 2, 1943 UNITED STATES. PATENT OFFICE TREATMENT OF HYDROCARBON OILS Jean Delattre Seguy, Washington, D. a, assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application November 17, 1941, Serial No. 419,402

3 Claims. (Cl. 196-10) a This invention relates to the treatment of hydrocarbon oils by combination cracking and gas polymerizing steps to effect a high degree of conversion of relatively heavy charging oils into light products of motor fuel boiling range and good antiknock characteristics.

More specifically, the invention comprises a series of cooperative steps in which the various fractions of raw oil charging stock and the partially cracked products are selectively treated to accomplish the objectives mentioned.

In one specific embodiment, the present invention comprises fractionating in a primary step a charging oil and cracked products to produce therefrom light gases, heavy readily liquefiable gases, gasoline, light reflux condensate, heavy reflux condensate and residuum; separately recovering said light gases and residuum, passing said heavy liqueflable gases to a subsequent residuum flashing step, condensing and recovering said gasoline, separately heating said light and heavy reflux condensates under conversion conditions of temperature and pressure in admixand fractionating in a secondary step to produce olefin-containing gases, gasoline and light and heavy reflux condensates, subjecting said olefincont-aining gases to contact with a polymerizing catalyst to form gasoline boiling range polymers from the oleflns in said olefin-containing gases,

fractionating said polymers in a tertiary step to.

produce gases, gasoline and polymers heavier than a gasoline, recovering polymer gasoline fractions and passing said heavy polymer fractions to said residuum flashing step.

In order to bring out the features of the present invention more definitely, the inter-related operations of the process will be described in connection with the attached drawing which diagrammatically illustrates an arrangement of apparatus in which the process may be conducted. 1

Referring to the drawing, a charging oil which may be a crude petroleum containing both gas and gasoline is introduced to the plant by way of line I containing valve 2 to a charging pump 3 which discharges through line 4 containing valve 5 into a fractionator 6 which operates to fractionate the charging oil'as well as the cracked products from reaction chamber 29 to be presently described. Fractionator 6 is of a design and capacity suitable for effecting a more or less sharp separation of the entering materials into overhead vapors comprising gases and gasoline, a relatively light reflux condensate material, a relatively heavy reflux condensate material and residual material unsuitable for cracking treatment. The overhead vapors comprising both fixed gases and gasoline pass through vapor line 7 containing valve 8 through a condenser 9 in which gasoline boiling range vapors are condensed and the products from the condenser pass through line I!) containing valve II to receiver [2, from which gasoline is withdrawn through line l3 containing valve 14. The gases from the receiver l2 pass through line l5 containing valve IE to a secondary fractionator I! which is designed to separate light gases comprising principally hydrogen, methane, ethane and ethylene from heavier gases comprising essentially propane, propene, butanes, and butenes, the light gases being vented through line 18 containing valve IQ for storage or use as fuel or for any other pumose to which they may "be suited. Heavier readily liqueflable gases pass 'the separate heating of light and heavy reflux condensates from fractionator ii along with corresponding reflux condensates from a subsequent cracking step under conditions best suited for cracking them for the production of optimum yields and quality of the gasoline from each. In accordance with the flow indicated in the drawing, a light reflux condensate may be withdrawn as a side out from fractionator 5 through line!!! containing valve 2| to a pump 22 which discharges through line 23 containing valve 24, to a tubular heating element 25 disposed to receive heat from containing valve 51.

. range product.

a furnace 26. Heating element 25 receives also light reflux condensate from line 12 as will be described at a later point.

A heavier reflux condensate is withdrawn at a lower level as a side cut from fractionator B and passed throughline 38, containing valve 3|,

to a pump 32 which discharges through a line 33 containing a valve 34 to a heating element 35 arranged to be heated by a furnace 36. Heating element 35 also receives a reflux condensate from line 11 as will be described at a later point.

The heated and partially cracked products from heating element 25 pass through line 21,-

ably is operated at a lower pressure than that employed in reaction chamber 29. Separator 45 receives heavy polymer fractions from line I00 and heavy readily liqueflable *gases from line I05 as will be subsequently described.

Residual material in separator 45 is withdrawnthrough line 48 containing valve 41 while the vapors pass into line 48. The vapor stream at this point may be split so that a portion passes through line 98 containing valve 49. and thence by way of line 58 containing valve 51 to fractionator 58. The remainder, and usually the major portion of the vapors, passing through line 59 containing valve 5| through a heating element 52 disposed to receive heat from a furnace53 in which they are subjected to further conversion under vapor phase conditions. The conversionproducts from heating element 52 pass through line 54 containing valve-55 and thence into fractionator 58 by way of line 56 These cracked products will contain high percentages of readily polymerizable olefins and fractionator 58 is preferably operated to produce gases of high olefin content, gasoline and both light and heavy reflux condensates. For eflecting these separations, it is comprised within the scope of the invention to use more than the single fractionator indicated in the drawing. Gasoline vapors pass through line 59 containing valve 80 and are condensed during passage through a condenser 6|, the condensed gasoline and any uncondensed gases passing through line 62 containing valve 53 to receiver '64 which is provided with a conventional gas release line 55 containing valve 56 and a gasoline drawofl! line 61 containing valve 68 for the recovery of gasoline boiling In accordancewith the invention, a light reflux condensate is removed as a-side cut from fractionator 58 through line 89 containing valve 10 and passed to pump II which discharges through line 12 containing valve I3 to heating element as previously described. Heavy reflux condensates from fractionator 58 are withdrawn through line H containing valve 15 to pump 18 which discharges-through line 11 containing valve I8 to heating element .35 as previously described.

Olefin-containing gases are removed from fractionator 58 through line 19 containing valve and passed through a reactor 8| containing preferably granular catalytic material capable of effecting substantial polymerization among the three and four carbon atom oleflns or the so-called higher oleflns." The polymerizing zone indicated diagrammatically as reactor 8| may commonly consist of a number of reactors in parallel or series connection through which the olefin-containing gases are passed in one or a group of reactors while the catalyst in another reactor or another group 01' reactors is undergoing regeneration by burning ofl deposited carbonaceous material with air or other oxidizing gas mixtures, the flow through the reactors be -ing alternated as the spent catalyst is regenerated and the fresh catalyst becomes spent.

Among the types of granular catalysts which may be used in the polymerizing zone designated by reactor 8! may be mentioned the socalled .solid phosphoric acid catalysts which are usually prepared by calcining pasty mixtures of phosphoric acids and a siliceous material such as kieselguhr to produce a solid cake which is ground and sized to produce granular catalyst particles. This procedure may be varied as desired by forming particles by the extrusion of the primary pasty mixtures to produce particles which are subsequently calcined. When using granular catalysts of this type, the temperature employed may vary from about 250 to about 550 F., but preferably from about 400 to about 500 F. in most cases while the pressure may vary from about to about 500 pounds per square inch.

Obviously, when the pressure utilized in the polymerizing zone is higher than that employed in the preceding fractionator, some type of pump or compressor will have to be used along the line of flow of line I9. Similarly, heating means will usually be necessary to bring the temperature up to that optimum for efiecting polymerization. Such pumps and heaters have been omitted from the present drawing in the interest of simplification.

Alternatively, with the solid phosphoric acid catalyst described, other granular catalysts of similar eflectiveness may be employed as desired, or liquid sulphuric acid may be used either in the so-called fhot" process or in the so-called cold process in which latter process esters first formed by the interaction of the oleflns and sulphuric acid at a relatively low temperature are subsequently decomposed at a higher temperature to yield reactive radicals which polymerize to form the desired polymer products. When using liquid polymerizing catalysts such as sulphuric acid, the actual construction of the polymerizing zone will require modification.

7 As indicated in the drawing, the total products from the polymerizing step comprising normally liquid polymers of various boiling ranges, residual three and four carbon atom hydrocarbons con- 'drawoif line 95 containing valve 96 for the removal of gasoline boiling range polymers.

In accordance with the present invention, polymers having a boiling range higher than gasoline are returned to the residuum flashing zone for eventual recycling to further cracking. Thus such heavy polymers are removed from the bottom of fractionator 84 through line 91 containing valve 98 to a recycle pump 99 which discharges into line I containing valve "II and leading to line I containing valve I06, the discharge line from ppmp I0, which in turn conducts the heavy polymers plus heavy gas from fractionating zone il back to separator 45.

To avoid complicating the schematic flow shown in the drawing, means for regulating the temperature of the emuent materials from reaction zone 8| before their admission to fractionator 84 are omitted as is also any subsequent stabilizing step which may be practiced upon the gasoline boiling range polymers collected in receiver 92.

While the temperatures and pressures employed at various points in the process may vary widely without departing from the scope of the invention, a few ranges may be mentioned as being preferable. In the two reflux condensate cracking zones designated as heating coils 25 and 35, the temperatures at the exit of the coils may be of the order of from 850 to 1050 F. although most commonly they will be of the order of from about 900 to about 1000" F., the temperature in coil 25 operating on light reflux condensates being usually higher than that employed in coil 35, operating upon heavier reflux condensates. Pressures in these two cracking coils and the succeeding reaction chamber may vary within the approximate range of from about 100 to about 500 pounds per square inch or higher. In separator or flash chamber 45, the pressure is preferably lower than that in reaction chamber 29 and may be less than 100 pounds per square inch. The temperature at the exit of vapor phase heating element 52 is commonly of from about 900 to about 1000 F., while the pressure is lower than that employed in the light and heavy reflux condensates cracking coils to favor greater production of olefin-containing gases.

The temperatures and pressure employed in the various fractionating zones may be determined by'the nature of the materials admitted for fractionation and the-closeness of the fractionation desired and the invention comprises the use of any necessary combinations of temperature, pressure, reflux condensate and capacity.

The gasoline boiling range materials produced at several points in the plant such as receivers I2, 64, and 92 may be separately collected-and blended in any desired proportions to produce gasolines of varying compositions and antiknock value.

' The following data are introduced to indicate the character of the results normally obtainable in the operation of the present process, but since the example is merely illustrative it is not to be considered as imposing undue limitations upon the proper scope of the invention.

A Mid-Continent crude oil may be charged toa plant such as the one indicated in the description in connection with the drawing, this crude oil being from the Mid-Continent producing area, having an A. P. I. gravity of about 36 and a natural gasoline content of 22 per cent. By following the general flow indicated with separate heating of light and heavy reflux condensates from the primary fractionator and the secondary fractionator operating upon vapor phase cracked products, followed by polymerization of the oleflnic gases from the vapor phase operation, the following yields may be obtained based on the crude charged.

Octane Product I Yield number Volume per cent lured gases 3 22 62 I l I no mere Straight-run residuum 20 Cracked residuum 5 1 Liquid equivalent.

The blend of the total gasoline from the-above operation may have an octane number of 70 and it will be seen that this represents 72 per cent of the crudeoil charged. I

I claim as my invention:

1. A hydrocarbon conversion process which comprises fractionating cracked va'pors. formed as hereinafter set forth, and charging oil to separate light gases, heavy readily liquefiable gases and gasoline and to condense and separate light reflux condensate and heavy reflux condensate, subjecting said light and heavy reflux condensates to cracking under independently controlled cracking conditions, supplying resultant conversion products from both cracking steps to a. reaction and separating zone and therein separating said cracked vapors from liquid residuum, combining at least a portion of said residuum with said heavy liquefiable gases, supplying the mixture to a reduced pressure vaporizing and separating zone and therein separating vapors from non-vaporous residue. cracking said vapors independently of the condensate fractions. fractionating the resultant conversion products from the last mentioned cracking step independently of said cracked vapors to separate olefin-containing gases and gasoline and to condense and separate light and heavy reflux condensates. combining the light and heavy reflux condensate formed inthe last mentioned fractionating step with the-corresponding fraction separated in the JEAN DELATTRE SEGU'Y. 

